As presented in the study, the men of Unit 101 were not ardent Nazis but ordinary middle-aged men of working class background from Hamburg, who had been drafted but found ineligible for regular military duty. After their return to Poland in June 1942 these men were ordered to terrorize Jews in the ghettos during Operation Reinhard, and in notable cases, committed wholesale massacres of all Polish Jews – men, women and children – as in the towns of Józefów and Łomazy. In other cases, they were ordered to merely kill a specified number of Jews in a given town or area usually helped by Trawnikis. The commander of the unit gave his men the choice (once) of opting out of this duty if they found it too hard. Almost all of them chose not to exercise that option. Fewer than 12 men opted out in a battalion of 500 willing executioners.

While the specifics of this book deal with killings performed by otherwise average men, the general implication of the book, consistent with the theories advanced by Stanley Milgram, is that when placed in a coherent group setting, most people will adhere to the commands given, even if they find the actions morally reprehensible. Additionally the book demonstrates that ordinary people will more than likely follow orders, even those they might personally question, when they perceive these orders as originating from an authority.

Browning also provides ample evidence to support the notion that not all of these men were hateful antisemites. He includes the testimony of men who say that they begged to be released from this work and to be placed elsewhere. In one instance, two fathers claimed that they could not kill children and thus asked to be given other work. Browning also tells of a man who demanded his release, obtained it, and was then promoted once he returned to Germany.

Ordinary Men achieved much acclaim but was denounced by Daniel Goldhagen for missing what Goldhagen considered the importance of a specifically-German political culture, characterized by what Goldhagen terms "eliminationist anti-semitism," in causing the Holocaust. In his book review published in the July 1992 edition of The New Republic, Goldhagen called Ordinary Men a book that fails in its central interpretation. Goldhagen's own controversial 1996 book Hitler's Willing Executioners was largely written to rebut Browning's book, but ended up being criticized much more.